Species diversity and human activities

Question 1

How are agricultural ecosystems controlled by humans?

Answer 1

Farmers often select species for particular qualities to make them more productive but the number of species and the genetic variety of alleles will reduce.

Question 2

What happens to other species if most of the area is taken up by one species?

Answer 2

Any particular area can only support a certain amount of biomass if most of the area is taken up by desirable species, other species are less likely to survive because there are less space and resources available to them.
Even if the species evolve to adapt to that change, the population of that species will reduce.
Also, pesticides are used to get rid of those unwanted species as they compete for light, mineral, water…

Question 3

Give examples where practices have directly removed habitats and reduced species diversity.

Give examples of indirect effect on species diversity.

Answer 3

• Removal or hedgerows and grubbing out woodland.
• Creating monocultures e.g. replacing natural meadows with cereal crops or grass for silage.
• Filling in ponds and draining marsh and other wetland.
• Over-grazing of land.
• Use of pesticides and inorganic fertilisers.
• A flow of silage stores and slurry tanks into watercourses.
• Absence of crop rotation and lack of intercropping or undersowing.

Question 4

How can we increase species and habitat diversity?

Answer 4

• Maintaining existing hedgerows at most beneficial height and shape.
• Plant hedges as a fence of field boundaries instead of putting up fences.
• Maintaining existing ponds and create new ones where possible.
• Leave wet corners of fields rather than draining them.
• Plant native trees in low species diverse area instead of in species-rich area.
• Reduce the use of pesticides - use biological control or genetically modified organism that are resistant to pests.
• Use organic instead or inorganic fertilisers.
• Use crop rotation, including nitrogen-fixing crop rather than fertilisers to improve soil fertility.
• Use intercropping rather than herbicides to control weeds and other pests.
• Create natural meadows and use hay rather than grass for silage.